If we ignore summoning Mahogara; what summoning technique is better. The 10 shadows and it's shikagami's or Geto's summoning of curses?
10s outside of Maho are all utility based.
They would be tremendous for any non top tier/high tier.
Take Megumi for example. He gets more attack power, tracking, more number of attacks, elemental attacks, RCT etc from 10s.
A top tier would already have most of those.
Geto's technique is capturing and then using curses. It's dependant on what curses they have already captured. I doubt any low level characters with Geto's ct would be able to capture any strong curses. So, it's only useful for already strong sorcerers.
So, 10s sans Maho is better for low tiers. Geto's ct is better for high tiers and above.